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Potassium concentration in whole blood

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of potassium, a mineral essential for heart function and nerve signaling, in your blood.

Quick summary

["Potassium levels help assess heart health and electrolyte balance."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
6298-4
Short code
Potassium Bld-sCnc
Synonyms
Potassium Bld-sCnc
Category
electrolyte
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
3.5
Ref high
5
Critical range
2.5 N/A – 6.5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84132
SNOMED
110742001
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order potassium testing to check for conditions like low potassium (hypokalemia), high potassium (hyperkalemia), or to monitor treatment for kidney disease, heart conditions, or other health issues.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it involves a blood draw. Avoid certain medications or supplements that could affect results.

How the Test Is Performed

A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight sting, but the procedure is quick and typically painless.

What the Results Mean

Results help determine if your potassium levels are within normal ranges or if further medical evaluation is needed. Abnormal levels may require adjustments to medications, diet, or treatment plans.

Reference range

Adult: 3.5-5.0 mmol/LN/A

Specimen: whole-blood

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Potassium plays a critical role in muscle function, nerve signaling, and maintaining fluid balance. Low potassium can cause weakness, irregular heartbeat, or muscle cramps, while high levels may lead to heart rhythm disturbances or severe weakness.

Short name

Potassium (K+)

Frequently asked questions

What causes potassium levels to be checked?
Potassium levels may be checked if you have symptoms like muscle weakness, irregular heartbeat, nausea, or if you’re taking medications that affect potassium, such as certain diuretics or heart medications.
How long does it take to get results?
Results are usually available within 1–2 business days, depending on your lab’s processing time. Your healthcare provider will discuss the findings with you during your follow-up visit.
Can diet affect potassium test results?
Yes, high-potassium foods (like bananas, spinach, or potatoes) or certain supplements may temporarily alter results. Your provider may recommend fasting or avoiding these before testing if needed.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy